testsuite: Xfail gcc.dg/tree-ssa/ssa-fre-100.c for ! natural_alignment_32
The test gcc.dg/tree-ssa/ssa-fre-100.c fails the
scan-tree-dump-not fre1 "baz" for at least m68k-linux,
pru-elf, and cris-elf according to posts on gcc-testresults.
GCC requires int-size-alignment for a target to see through
the "int *" dereference and perform value-numbering. See
comments in PR91419 and also the recent patch to
gcc.dg/tree-ssa/pr100359.c. This is a flaw in gcc rather
than the target, so prefer an xfail rather than skipping
the test.
* gcc.dg/tree-ssa/ssa-fre-100.c: XFAIL for ! natural_alignment_32.